NowSignage RDM: How Remote App Updates Work

NowSignage lets you send an 'Update app' command to individual screens or in bulk. Whether a device can install the update depends on the permissions its operating system allows, not on how NowSignage sends the command.

This guide explains how Remote Device Management (RDM) updates the NowSignage player app on each platform and why Android requires a separate RDM app. It is intended for partners, integrators, and our pre-sales and support teams, and complements the existing RDM and Android RDM guides. RDM guide and Android RDM guide.

• Summary 

Modern operating systems restrict which apps can install or replace software and how they do it. NowSignage follows the update method each platform permits.

• Samsung Tizen 6.5/7.0 and Sony Bravia provide manufacturer signage APIs that let the NowSignage app request its own update. The display firmware performs the install, so no extra app is needed. The same APIs exist on Tizen 4.0/5.0 and LG webOS 6.0 and later, and we plan to implement updates there in the near future, again with no separate app.
• Windows and macOS run NowSignage as an Electron desktop app, which can download and install its own new version. Remote updates need app 5.3.49 or later on Windows and 5.3.20 or later on macOS. Linux, also Electron, is on the roadmap.
• Android has no single signage update API that works across manufacturers. NowSignage therefore uses a separate RDM app with root (superuser) permissions to install updates without on-screen confirmation. The RDM app keeps running while Android replaces the player app, then relaunches it. This means NowSignage remote app updates require both a rooted Android device and the RDM app.

• How an update command reaches a screen

Every platform shares the same journey up to the install itself; only that last step is platform-specific.

1. A user sends 'Update app' from the CMS, for one screen or in bulk via Mass Management > RDM Actions. The command is stored as Pending and can still be cancelled.
2. On app 5.3.20 and above, the player collects queued commands on its standard 5-minute poll. Offline screens collect them when they reconnect.
3. The command shows as Acknowledged. This confirms the device received it, not that the install succeeded.
4. The player hands the update to its platform's install route (next sections). Updates always go to the latest released NowSignage version for Android. For Windows, MAC or Tizen, the user can define the version by entering in the app install URL within the RDM command area (the latest app is always advised).

The CMS only offers commands the screen's OS supports, based on device analytics from app 5.3.20 and above.

The first four steps are identical on every platform; only the install route differs, and Android's is the only one that needs a separate app.

• Remote app update support by platform

Five platforms support remote app updates today, with Tizen 4.0/5.0, LG webOS and Linux planned; only Android needs an additional app to do it.

• Samsung Tizen (SSSP)

On Tizen 6.5 and 7.0 (app 5.3.20 or later), the NowSignage app requests its own update through Samsung's Smart Signage Platform (SSSP) APIs, so no separate RDM app is needed.

Samsung builds signage-specific device APIs into the display firmware and makes them available to signage apps. When the player receives the 'Update app', it asks the device to fetch and install the latest NowSignage package. Because the device performs the install outside the running app, the old version can be replaced cleanly and the new one relaunched.

This same principle applies to Sony Bravia and LG webOS: each manufacturer controls both the OS and the hardware, so one vendor API covers its whole display range.

On Tizen 4.0/5.0 and LG webOS 6.0 and later, the same manufacturer APIs exist and we plan to implement remote app updates in the near future. Neither will require a separate RDM app. Reboot and on/off timers already work on Tizen 4.0/5.0.

• Windows and macOS (Electron)

On Windows and macOS the player is an Electron desktop application, and Electron supports apps updating themselves, so no separate RDM app is needed.

Desktop operating systems let a normally installed application update its own files. Electron's update framework uses this: the app downloads the new version, a small updater helper bundled with the installation swaps in the new files once the app closes, and the new version starts.

Remote app updates are supported from app 5.3.49 on Windows and from app 5.3.20 on macOS. On both platforms the 'Reboot' command restarts the NowSignage app rather than the computer. Linux also runs the player as an Electron app; remote updates there are under review and on our roadmap, and are expected to work in a similar way to Windows.

• Android: why a separate RDM app and root are needed

Remote app updates on Android require permission to install without on-screen confirmation and a separate process that stays running while the player app is replaced. The main NowSignage app cannot reliably handle both tasks itself. On rooted devices, the NowSignage RDM app uses root permissions to install the update and remains running to relaunch the player afterwards.

• Silent installs are reserved for privileged apps

A standard Android app can request an APK installation, but someone must approve it through an on-screen confirmation prompt. On unattended signage devices, no one is available to confirm the installation, so the update cannot proceed. Installing without that prompt is reserved for privileged apps, such as those built into the device firmware and signed by its manufacturer. NowSignage isn't part of any manufacturer's firmware, so across the wide range of Android hardware our customers use, root (superuser) access is the route that works consistently. With it, the RDM app uses Android's own package manager to install the update silently. The Reboot command needs the same elevated access.

• An app can't safely replace itself while it's running

When Android installs a new version of an app, it first stops that app. If the player installed its own update, Android would close it partway through, leaving nothing running to confirm the install, relaunch the player or recover from a failure. The RDM app is a separate app, so it keeps running throughout: it installs the new APK, then relaunches NowSignage. If an update fails, it relaunches the existing version so the screen keeps playing.

• A watchdog has to live outside the app it watches

A crashed app can't restart itself. The RDM app also acts as a watchdog, relaunching NowSignage 30 seconds after it closes or crashes. This works on Android 7.1 and above, whether or not the device is rooted.

• Why there's no Samsung-style API on Android

Tizen, webOS and Bravia are each one manufacturer's OS on that manufacturer's displays. Android signage hardware comes from many manufacturers, each with its own firmware and, in some cases, its own management tools. There's no single install API that works across all of them.

• Why can't NowSignage just make one API call to update everything?

Sending an update to every screen in one action is already possible; the limit is what each device is permitted to do once it receives the command.

• The bulk command exists. Mass Management > RDM Actions sends 'Update app' to any selection of screens at once. An API call would place the same command in the same queue.
• A command is a request, not an install. The NowSignage cloud can't reach into a device and install software. Each device collects the command and carries it out with the permissions its operating system grants.
• Install permission belongs to the OS vendor. Samsung, LG and Sony grant it through their signage APIs, and desktop operating systems grant it to installed apps. Standard Android doesn't, which is why rooted devices and the RDM app are needed.
• Not every device can act on it yet. Non-rooted Android can't take remote app updates however the command is sent. Tizen 4.0/5.0, LG webOS 6.0 and later, and Linux are planned. BrightSign app updates are handled through BrightSign's BSN.cloud, not currently the NowSignage CMS.

• FAQ 

How quickly does an update happen?

The device collects the command on its next 5-minute poll; download and install time then depends on the device and its network.

Does 'Acknowledged' mean the update worked?

No, only that the device received the command. Confirm the new version in screen analytics (app 5.3.20 and above).

What happens if an Android update fails? The RDM app relaunches the existing NowSignage version so the screen keeps playing.

Our Android devices aren't rooted. What are the options?

Ask your device manufacturer whether rooted firmware is available, or choose supported hardware from the verified device list. If rooting is not an option, install updates on site, for example via USB, or use a compatible third-party remote device management or mobile device management (RDM/MDM) tool, such as TeamViewer. Watchdog and screenshot features remain available on non-rooted devices.